The present application relates to the field of x-ray and computed tomography (CT). It finds particular application with CT security scanners. It also relates to medical, security, and other applications where identifying objects of interest and in particular potential granular objects (e.g., small, substantially uniformly shaped objects) would be useful.
Security at airports and in other travel related areas is an important issue given today's sociopolitical climate, as well as other considerations. One technique used to promote travel safety is baggage inspection. Often, an imaging apparatus is utilized to facilitate baggage screening. For example, a CT device may be used to provide security personnel with two-dimensional and/or three-dimensional views of objects. After viewing images provided by the imaging apparatus, security personnel may make a decision as to whether the baggage is safe to pass through the security check-point or if further (hands-on) inspection is warranted.
Current screening techniques and systems can utilize automated object recognition in images when screening for potential threat objects inside luggage. These systems can extract information about an object(s) from an image(s), and compute properties of the object(s) based upon the extracted information. Properties of examined object(s) (e.g., density, shape, atomic characteristics, etc.) can be compared to properties of threat items, non-threat items, or both classes of items to identify the examined object(s) and/or to classify the object(s) (e.g., as a potential threat or non-threat item).
Certain types of non-threat items, such as vitamins, candy, and/or other granular objects, for example, are traditionally difficult to distinguish from threat items because such non-threat items share similar density, shape, and/or other morphological characteristics with threat items, and thus are mistakenly characterized as potential threat items. Such a mischaracterization is commonly referred to in the art as a false alarm. It will be appreciated that when an item is flagged as a potential threat item, even if it is a false alarm, additional security precautions, such as a manual search of the baggage, are taken to inhibit passage of a threat item through security. Thus, to increase throughput at a security checkpoint, for example, it is beneficial to decrease the false alarm rate.